Olympian Roberto Carcelén wouldn’t be competing in Sochi if it weren’t for his wife, Kate. She was the one who introduced him to skiing after he gave up elite surfing in Peru to move to Seattle and marry her. She convinced him that it was like surfing on frozen water.

When Carcelén skis for his native Peru on the cross-country track this month, however, Kate and their daughter will be at home. Amid reports about the possibility of terrorist attacks at the Winter Games, they decided it would be safer that way — and less stressful.

“I’m going to be up training in the mountains, while the family would be down in the city outside the Olympic rink,” Carcelén told CNN. “So that puts a lot of pressure on me as an athlete.”

The security threat during the Olympics isn’t hypothetical. As has been widely reported, the Winter Games are being held in a country with an active insurgency capable of coordinating devastating attacks, including two suicide bombings in December. In the past seven months, Chechen terrorists have twice issued statements targeting the Olympics.

But if there’s a terrorist attack during the Games, it’s far more likely to happen outside Sochi.

That’s because President Vladi­mir Putin has gone all out to secure the Olympic villages and venues. His “ring of steel” includes 100,000 police officers, soldiers and secret service personnel; drones and attack helicopters; and advanced ground-to-air missile systems. Russia’s surveillance state will be in full force, operating tens of thousands of security cameras and monitoring phone calls and e-mails. Visitors to the Olympic Villages will have to show pre-approved “Olympic passports.”

While the Olympic sites will be brimming with security, much more vulnerable are the routes in and out of Sochi. Attacks on transportation are the signature of Russia’s current terrorist nemesis, the Caucasus Emirate. It claimed responsibility for derailing a high-speed train in 2009, sending a pair of female suicide bombers to strike Moscow’s metro during rush hour in 2010 and targeting Russia’s largest airport in 2011. It has also targeted security checkpoints, and there will be many on the road to Sochi.

The group may figure that an attack at such a checkpoint, on a bus or on the railroad tracks would have the same symbolic effect as striking within Sochi itself.

Air is the most defensible route to the Winter Games, and it’s how the majority of the 15,000 Americans attending the event will get there. One can fly into the newly expanded Sochi-Adler International Airport from Frankfurt, Istanbul, Munich, Moscow, St. Petersburg and several smaller Russian cities. Russia’s airports, with their guns, gates and guards, should be relatively safe. But the planes themselves are vulnerable to shoulder-fired missiles, also known as man-portable air-defense systems (MANPADS), a weapon terrorist groups have used to target civilian aircraft. Ominously, Russia in 2012 discovered large weapons caches near Sochi that included several MANPADS.

On the ground, bus and rail are the primary travel options. Sochi hugs the Black Sea for 92 miles, and there are only two main arteries into the city: one highway and one rail line. By road, the nearest intersection is 100 miles northwest of Sochi along the winding M27 highway, through villages and mountain switchbacks. And as of Jan. 7, drivers with out-of-town license plates have had to leave their cars 60 miles away and take shuttle buses in.

The rail line winds up the coast some 75 miles to the town of Tuapse, then splits off through mountains and into one of Europe’s largest primeval forests. Beyond that point, a spider web of transport hubs, connecting railways, and sleepy stops in towns and tiny villages links Fortress Sochi to the city of Krasnodar and the rest of the world. Of course, Winter Games are often held in hard-to-reach mountain towns, but the journey to Lake Placid, Nagano or Lillehammer did not wind through terrorist stomping grounds.

Both of these fragile ground-transport ribbons are vulnerable to attack. A well-placed obstruction on a hairpin turn would delay traffic for hours. Combined with a terror strike, it would decimate any sense of safety at the Games, cast a pall over Sochi and shake Putin’s image as a man with an iron grip. Blast roadways and train tracks simultaneously, and one of the largest sporting events in Russia’s history becomes a disaster.

Russian and U.S. security officials are certainly aware of these vulnerabilities. Russia has informally requested use of the Pentagon’s sophisticated anti-bomb equipment to suppress threats along the roads and rails. Meanwhile, Matthew Olsen, director of the National Counterterrorism Center, told the Senate on Wednesday that the greatest threat to the Games is terrorists hitting “softer targets ” around Sochi. The State Department has warned athletes to avoid wearing Team USA gear outside of Olympic venues. The U.S. military has positioned two naval ships in the Black Sea and has aircraft on standby in Germany in case it needs to evacuate Americans quickly.

The Olympics’ Closing Ceremonies on Feb. 23 coincide with the 70th anniversary of Stalin’s brutal deportation of the Chechen and Ingush populations from the Caucasus. Almost 500,000 men, women and children were rounded up in freight trains and sent to Central Asia. Up to half of them perished along the way. Terrorists might try to exploit the symbolism of the day and of the Olympics for nefarious ends, and transportation in and out of the Games may be the place they’ll choose to make their presence known.

Let’s hope we remember the Sochi Games for the triumph of the athletes, not of the terrorists.

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Aki PeritzAki Peritz is a former CIA counterterrorism analyst and coauthor of "Find, Fix, Finish: Inside the Counterterrorism Campaigns that Killed bin Laden and Devastated Al Qaeda." The opinions he expresses here are his own, not those of his employer. Follow